Antinociceptive effect of R-(+)-hyoscyamine on the conjunctival reflex test in rabbits

Understanding Central Nervous System Effects of Deliriant Hallucinogenic Drugs through Experimental Animal Models

Hallucinogenic drugs potently alter human behavior and have a millennia-long history of use for medicinal and religious purposes. Interest is rapidly growing in their potential as CNS modulators and therapeutic agents for brain conditions. Antimuscarinic cholinergic drugs, such as atropine and scopolamine, induce characteristic hyperactivity and dream-like hallucinations and form a separate group of hallucinogens known as "deliriants". Although atropine and scopolamine are relatively well-studied drugs in cholinergic physiology, deliriants represent the least-studied class of hallucinogens in terms of their behavioral and neurological phenotypes. As such, novel approaches and new model organisms are needed to investigate the CNS effects of these compounds. Here, we comprehensively evaluate the preclinical effects of deliriant hallucinogens in various animal models, their mechanisms of action, and potential interplay with other signaling pathways. We also parallel experimental and clinical findings on deliriant agents and outline future directions of translational research in this field.

Antinociceptive Effects of the Aqueous Extract of Brugmansia suaveolens Flowers in Mice

The infusion of Brugmansia suaveolens, popularly known as trombeteira or cartucheira, has been used to treat pain in Brazil. The present study was conducted to test for its antinociceptive effects using the abdominal-writhing, formalin, tail-flick, and hot-plate tests in mice. The aqueous extract from B. suaveolens flowers administered intraperitoneally at doses of 100 and 300 mg/kg body weight significantly inhibited acetic acid-induced abdominal constrictions. An increase in hot-plate latency was also observed in animals receiving both doses (100 and 300 mg/kg). In the formalin test, both doses from the aqueous extract inhibited the first (0-5 min) and second phase (20-25 min). Tail-flick assays demonstrated that treatment of animals with plant extract induced attenuation of the response. These results suggest that the aqueous extract from B. suaveolens flowers produced antinociceptive effects, as demonstrated in the experimental models of nociception in mice. This supports popular medicinal uses of this plant as an analgesic.